Electrical condenser.



UNITED sTAtr s PATENT onnron.

WILLIAM W. DEAN, OF ELYRIA, OHIO, ASSIG-NOR TO THE DEAN ELECTRIC COMPANY,

' OF ELYIRIA, OHIO, A. CORPORATION OF OHIO.

ELECTRICAE CONDENSER.

Specification of Letters Patent.

Patented Aug. 2, 1910.

\ Application filed January 28, 1909. Serial No. 474,772.

To all whom it may concern:

- Be it known that I, WILLIAM W. DEAN, a citizen ofthe United States, residin Elyria, in the county of Lorain and tate of Ohio, have invented certain new and useful Improvements in Electrical Gondensers, of which the following is a full, clear, and concise description, reference being had 'to the accompanying drawings, forming a part of this' specification.

My invention'relates to an electric condenser commonly used in connection with electrical apparatus, such as telephone exchanges, etc., in which it is desirable to store charges of electricity, as desired.

Heretofore in the art it has been customary to construct condensers of this class by assembling two metallic sheets or plates with interposed sheets or thicknesses of dielectric between them. It has been found convenient in the past to accomplish this result by using strips of tin foil to form the conducting surfaces and using strips of thin paper between the strips of tin foil to prevent their coming in contact, and winding the several strips together in the form of a roll, 'as a result of which a considerable amount of surface is availablefor retaining the electric charge.

In constructing condensers in the manner described, it has frequently happened in the that particles of dirt or conducting matter would be wound in between the several layers of paper and tin foil in such a manner that the subsequent manipulation of the condenser in preparing it for use would cause the particles to puncture the dielectric between adjacent conducting surfaces and thus short the condenser. It has been customary in the past to clear condensers of short circuits thus established by burning out the conducting path thus formed between the strips of tin foil by means of a bank of condensers which have been charged from a source of direct current or by applying the direct current to the terminals of the condenser to be cleared. In many cases this process fails to clear the condenser of the short-circuit owing to the fact that the conducting path between the layers of tin foil permits a sufiicient current to flow to melt a considerable quantity of the foil before the which the tin runs together through the opening formed in the dielectricandapermai are very much lessliable to be short-cir- 11 vantage.

nent short-circuit is the result, which cannot be burned out, and the condenser must be thrown away.

It 'is an object of this invention to improve the construction of electrical condensers in such a manner that a suflicient amount of metal is not available during the burning out process to permanently short-circuit the metallic conducting surfaces of the con-. denser. This I accomplish by using but one strip of tin foil and in combination with such strip, to constitute the second conducting strip of the condenser, a strip of thin paper to one side of which conducting material in finely divided condition is so applied that it forms a continuous conducting surface. The strip of tin foil and the coated strip of paper are wound together in the form of a roll in accordance with any of the ing in contact with the other conducting surface. After the rolls are formed, the condenser may be finished in any of the well known ways common in the art, which are not indicated in detail here since they form no part of this invention.

As a result of the improved construction described, the amount of metal which is subject to the heating action of burning out a short-circuit is greatly reduced and shortcircuits that would otherwise permanently short-circuit the condenser and destroy the sa ne by the'burning out process, as described above, may be readily removed since the amount of metal melted in the process is very small comparatively and comes almost entirely from the strip of coated paper. The improvement resulting from this is of great value, especially in connection with telephone work, since in such work condensers are frequently mounted together in considerable number, and it is frequently necessary to burn out short-circuits in these condensers after they are placed in use, since the imperfections were not of a serious enough nature to give any indication of their presence at the time of testing the condensers at the factory. The possibility of clearing these condensers of short-circuits that may develop in this manner is a great ad- Furthermore, condensers constructed in'accordance with my invention cuited by the accidental puncturing of the dielectric-by the accidental application of high voltage ringing current or accidental crossing of the conductors connected to the condensers with high voltage power circuits;

In constructing my improved condenser the strip coated with finely divided conducting material may be prepared and used in a number of ways, as, for instance, the strip may be coated on both sides, if desired, and

.one side may be placed directly in contact are as follows:

Figure 1 shows, in perspective, a roll formed by winding a single strip of coated paper, a strip of tin foil and a single strip of plain paper together in such a manner that the conducting surfaces are kept entirely separate from each other; F1g. 2 shows an arrangement similar to Flg. 1 1n which an additional sheet of plain paper 1s used to afford further separation between the conducting surfaces.

Similar numerals refer to similar parts throughout the views.

As shown in Fig. 1 a strip of paper 1 1s coated, .as indicated at 2, with a conducting material in finely divided condition in such a manner that there is a portion of the strip along each edge that is not coated. The conductin material may consist in finely divided tin or any other suitable material that possesses high electrical conductivity and that may be reduced to finely divided condition. A strip of tin foil 3 ofpractically the width of the coating 2, and a strip of plain paper 4 are wound with the coated strip 1 into a roll 5, in such a manner that the strip of tin foil 3 has, on each side of it, a plain uncoated surface of paper, as a result of which the strips of paper 1 and 4: serve to prevent the strip of tin foil?) coming in contact with the coating 2, either directly or as a result of the winding. Suitable terminals 6 and 7 are secured to the inner ends of the conducting surfaces 2 and 3 by means of which connections may be made to the terminals'of the condenser when the same is finished for use.

The arrangement shown in Fig. 2 is similar to that shown in Fig. 1 with the diflerence that additional strips of paper 8 and 9, are used on the two sides of the strip of Q w tts tin foil 3, as a result of which the conducting surfaces of the condenser are separatedmore thoroughly from each other, or, in other words, the electrical insulation between such surfaces is greater than with the arrangement shown in Fig. 1.

It is to be understood that the rolls rangements described above may be subsequently treated in any of the well known ways, as, for instance, boiling in paraffin, pressing, placing in suitablecases, and the like by which the finished condenser is produced. These subsequent steps in the con struction of the condenser, however, form no part of the present invention, which consists essentially in the construction .and arrangement of the strips forming the condenser. I

While I have shown my invention in the particular embodiment herein described, I do not,however, limit myself to this particular arrangement, but desire to claim any equivalent arrangement that will suggest itself to those skilled in the art.

What I claim is:

1. In an electrical condenser, the combination of a strip of paper coated on one side with finely divided conducting material, said strip of paper adapted to act as an insulator at low voltages, but adaptedto be punctured at. high voltages, said finely divided conducting material adapted to be dissipated at the puncture to isolate said puncture from the remaining finely divided conducting material .and a strip of low resistance metallic foilall wound together in the form of a roll, the strip of paper being interposed be- .tween the layer of finely divided material and-the foil and terminals connected one to themetallicfoil and one to the finely divided conducting material.

2. In an electrical condenser, the combination of two conductors and an insulator, said insulator being puncturable at high voltages to permit a dlscharge of electricity between said conductors, one of-said conductors composed .of a relatively high resistance surface of finely divided conducting material, the

finely divided conducting material in the-- vicinit of a puncture adapted to be dissipated y a high voltage discharge to isolate the puncture from the undissipated surface of said material, said second conductor consisting of a low resistance metallic surface, which is undisturbed by the discharge which punctures the said insulatorand dissipates the finely divided conducting .material and a plurality of strips of insulating paper, all wound together in the form of a roll, the insulator being between the conductors and a stripof paper on the outside of each conductor and terminals, one connected to each conductor.

3. In an electrical condenser, the combinaformed in accordance with any of the artion of two conductors, and an insulator therebetween, the insulator being of a greater area than the conductors, said insulator being puncturable at high voltages, one of said conductors consisting of a strip of finely divided conduct-in material adapted to be dissipated by a big voltage discharge when the msulator is punctured, thereby to isolate the puncture from the remaining conducting material, the other of said conductors consisting of a stri of low resistance metallic foil, which is not disturbed by the said high voltage discharge, said strips being placed together with the edges of the strip of paper projecting beyond the edges of the foil and the whole wound together in the form of a roll and a terminal for each of said conductors.

i. In an electrical condenser the combina tion of a strip of aper coated on one side with finel divide conductin material, a stri of 0w resistance meta ic foil, the fine y divided conducting material adapted to be dissipated at temperatures at which the foil is undisturbed, the two wound together in the form of a roll with the paper between the metallic surfaces and terminals for each conductor.

5. In an electrical condenser the combination of a plurality of strips of paper, one of which is coated on one s1de w1th finely divided conductin material, a strip of low resistance metal ic foil, the finely divided conducting material adapted to bedissipated by electrical discharges, by which the metallic foil is undisturbed, said stri s being wound together in the form of a rol a strip of paper being placed between the strips of conductors and a second upon the outside of the same and a terminal for each conductor.

In witness whereof, I hereunto subscribe my name, this 21st day of January, 1909.

WILLIAM W. DEAN.

Witnesses:

A. D. T. LIBBY, W. B. MANSON. 

